Make your office space available for local Alfresco meetups. If there isn’t a regular meetup in your area, start one and keep it going quarterly.

If you customize Alfresco, take the customizations that don’t represent a competitive advantage to your business and contribute them to the community as freely-available addons. If you don’t want to take the time to package it up as a formal add-on, at least stick your code on github or a similar public code repository.

Similar to the above, if you hire systems integrators, word your contracts such that they can contribute the code they write for you to the community. (Often the default language assigns IP ownership to the hiring party).

If you choose Community Edition, give your time to the Order of the Bee so that you can help others be successful running Community Edition in production. The Order is particularly interested in Community Edition success stories at the moment.

File helpful bug reports and make sure they are free of information specific to your business so that Alfresco will keep them public.

If you not only find a bug but fix it, contribute the patch. One way to do that is to create a pull request on GitHub in the Alfresco Community Edition project then reference that pull request in an Alfresco Jira.